EP1537655B1 - Multiple resonance filter - Google Patents

Description

The invention relates to a multiple-resonance filter containing a plurality of multilayer capacitors.

From the publication US 5898562 a multiple-resonance filter is known, in which two adjacent multilayer capacitors of different capacitance are integrated in a multilayer component. This device is used to attenuate spurious signals at two frequencies dictated by the capacitances of the two capacitors. The known device has the disadvantage that the attenuation has relatively poor values.

Furthermore, from the document US 6,304,156 B1 and EP 1215748 A1 Multiple resonance filter known.

It is therefore an object of the present invention to provide a multiple resonance filter having good attenuation values.

This object is achieved by a multiple resonance filter according to claim 1. Advantageous embodiments of the invention can be found in the further claims.

A multi-resonance filter is disclosed, which is a multilayer electrical component. It contains at least three multilayer capacitors arranged side by side. The multilayer capacitors have at least two mutually different capacitances. The two outer of the multilayer capacitors lying in a row have the same capacity.

By constructing the multiple resonant filter with capacitors arranged side by side in a row and by forming capacitors of equal capacitance at the two edges of the row, it can be achieved that decoupling of the electromagnetic fields takes place in the filter the damping behavior is improved at the individual resonance frequencies of the filter.

This results in the advantage that the multiple resonance filter has an improved damping behavior.

In an advantageous embodiment of the multiple resonance filter, the multilayer capacitors are connected in parallel to one another. Due to the parallel connection, the filter properties of the multiple resonance filter can be additionally improved.

In one embodiment of the multilayer component, a base body is provided, which has a stack of superimposed dielectric layers. Between the dielectric layers electrode layers are arranged. This embodiment has the advantage that, for the realization of the multiple resonance filter, the well-known technology of the multilayer capacitors can be used.

Multilayer capacitors are generally constructed so that comb-like interdigitated electrode stacks are formed in the interior of the device by internal electrode layers. Each stack of internal electrodes is connected in common with an external contact.

In one embodiment of the multiple resonance filter, external contacts of the electrode layers are arranged on the end faces of the base body.

In another embodiment of the multiple resonance filter, electrode layers belonging to different capacitors are connected to one another in the interior of the main body. This can be done in an advantageous manner in the interior of the body, ie in the interior of the device, a parallel connection of the individual capacitors.

In one embodiment of the multiple resonance filter, electrode layers extend in the longitudinal direction of the main body. In another embodiment, electrode layers extend transversely to the longitudinal direction of the main body.

In one embodiment of the multiple resonance filter, external contacts of the electrode layers are arranged on side surfaces of the base body. This embodiment of the filter makes it possible to assign the external contacts individually to each individual capacitor of the multilayer component and to perform the desired cladding of the capacitors with one another only on the board to be equipped with the component. As a result, the flexibility of the possible uses of the device is advantageously increased.

In particular, it is made possible by the fact that the multilayer capacitors are connected in parallel to each other outside the main body.

In one embodiment of the filter, three multilayer capacitors are provided. In another embodiment of the filter, four multilayer capacitors are provided, wherein the two middle multilayer capacitors have the same capacitance.

In one embodiment of the filter, the multilayer capacitors form LC filters together with the inductances of the electrode layers or together with the inductances of the leads to the electrode layers. By adding inductors to the device, the filter characteristics of the device can be further improved. By deriving the main contribution of the inductances required for the filter from the leads and the electrode layers, it is possible to set the inductance to a desired level by means of a corresponding configuration of the electrode layers or the leads to the electrode layers.

In one embodiment of the filter, the dielectric layers contain a barium titanate based capacitor ceramic. For example, a so-called "COG" ceramic is considered as the dielectric layer. Such a material would be, for example, a (Ba, Sm) NdTiO ₆ ceramic. But it is also a "X7R" ceramic into consideration, for example, doped barium titanate.

In another embodiment, the dielectric layers contain a capacitor material with varistor effect.

As a ceramic material with varistor effect is for example a ceramic material based on ZnO-Bi or ZnO-Pr into consideration. Such dielectric layers have the advantage that, in addition to the capacitor, they integrate a varistor into the multilayer component as a further component.

Moreover, it is also possible to combine capacitor ceramics and ceramics with varistor effect within a single device with each other.

In one embodiment of the filter, the base body has a base area which is smaller than 6 mm ² . This embodiment has the advantage that the space requirement of the device is very small, which is advantageous for miniaturized circuits.

In one embodiment of the filter, electrode layers belonging to the two outer multilayer capacitors have equal areas. This embodiment has the advantage that the requirement for equal capacitances of the outer multilayer capacitors can be realized particularly easily by the same areas.

• Figur 1 zeigt ein Mehrfachresonanzfilter in einem schematischen Querschnitt.
• Figur 2 zeigt die Einfügedämpfung des Bauelements aus Figur 1.
• Figur 3 zeigt beispielhaft ein weiteres Mehrfachresonanzfilter in einer perspektivischen Außenansicht, wobei die Außenansicht mehrere Möglichkeiten für die innere Struktur umfaßt.
• Figuren 31, 31A, 31D zeigen beispielhaft die innere Struktur für ein Bauelement mit einer äußeren Struktur gemäß Figur 3.
• Figuren 32, 32A, 32D zeigen die innere Struktur eines weiteren Filters, dessen äußere Struktur in Figur 3 dargestellt ist.
• Figuren 33, 33A, 33D zeigen beispielhaft eine innere Struktur eines weiteren Bauelements, dessen äußere Struktur in Figur 3 gezeigt ist.
• Figuren 34, 34A, 34D zeigen beispielhaft die innere Struktur eines weiteren Filters, wobei dessen äußere Struktur durch Figur 3 gegeben ist.
• Figur 4 zeigt beispielhaft die äußere Struktur für ein Filter, wobei diese Struktur für Filter, deren innere Struktur in den Figuren 41, 41A und 41D sowie in den Figuren 42, 42A und 42D gezeigt ist, gilt.
• Figuren 41, 41A, 41D zeigen die innere Struktur für eine Ausführungsform des Filters, dessen äußere Struktur durch Figur 4 gegeben ist.
• Figuren 42, 42A, 42D zeigen die innere Struktur für ein weiteres Filter, dessen äußere Struktur durch Figur 4 gegeben ist.
• Figur 5 zeigt die äußere Struktur eines Filters beispielhaft in einer perspektivischen Ansicht, wobei die äußere Struktur für eine Vielzahl von inneren Strukturen gültig ist.
• Figuren 51, 51A, 51D zeigen die innere Struktur eines Filters, dessen äußere Struktur durch Figur 5 gegeben ist.
• Figuren 52, 52A, 52D zeigen die innere Struktur eines weiteren Filters, dessen äußere Struktur durch Figur 5 gegeben ist.

The invention is explained in more detail below on the basis of exemplary embodiments and the associated figures:

• FIG. 1 shows a multiple resonance filter in a schematic cross section.
• FIG. 2 shows the insertion loss of the device FIG. 1 ,
• FIG. 3 shows by way of example a further multiple resonance filter in an external perspective view, wherein the external view includes several options for the internal structure.
• FIGS. 31, 31A, 31D show by way of example the internal structure for a device with an outer structure according to FIG. 3 ,
• Figures 32, 32A, 32D show the inner structure of another filter whose outer structure in FIG. 3 is shown.
• FIGS. 33, 33A, 33D show, by way of example, an internal structure of a further component whose external structure is in FIG. 3 is shown.
• Figures 34, 34A, 34D show by way of example the internal structure of another filter, wherein the outer structure of FIG. 3 given is.
• FIG. 4 shows by way of example the external structure for a filter, this structure for filters whose internal structure in the Figures 41, 41A and 41D as well as in the Figures 42, 42A and 42D is shown applies.
• Figures 41, 41A, 41D show the internal structure for an embodiment of the filter whose external structure is given by FIG.
• Figures 42, 42A, 42D show the inner structure for another filter whose outer structure is through FIG. 4 given is.
• FIG. 5 shows the outer structure of a filter by way of example in a perspective view, wherein the outer structure is valid for a variety of internal structures.
• FIGS. 51, 51A, 51D show the internal structure of a filter, its external structure through FIG. 5 given is.
• Figures 52, 52A, 52D show the inner structure of another filter, its outer structure through FIG. 5 given is.

FIG. 1 shows a multiple resonance filter having a base body 1. Inside the main body 1 capacitors K1, K2, K3, K4 are arranged side by side in a row. Each of the capacitors K1, K2, K3, K4 is respectively connected to a first capacitor terminal 211, 212, 213, 214 and to a second capacitor terminal 221, 222, 223, 224. Each belonging to a capacitor K1, K2, K3, K4 first capacitor terminals 211, 212, 213, 214 are connected by a contact 31 with each other electrically conductive. Each of a capacitor K1, K2, K3, K4 belonging second capacitor terminals 221, 222, 223, 224 are electrically conductively connected to each other by a contact 32. Through the contacts 31, 32, a parallel circuit of the capacitors K1, K2, K3, K4 is realized. The capacitors K1, K2, K3, K4 are designed in terms of their capacitance C1, C2, C3 so that the capacitors K1 and K4 have the capacitance C1, that are equal in capacity. The capacitors K2 and K3 have the capacitance C2 and C3. The capacitances C2, C3 may be the same or different.

FIG. 2 shows the attenuation behavior of the multiple resonance filter FIG. 1 in the event that the two capacitors K2 and K3 off FIG. 1 have the same capacity C2. In FIG. 2, the attenuation S in the unit decibel is plotted against the frequency f, measured in GHz, of an electrical signal which was applied to the filter. It is in FIG. 2 to recognize that at the resonant frequencies f1 and f2 a very high attenuation was measured less than -40 dB. This shows that the multiple resonance filter described in this application has very good damping characteristics. The two resonance frequencies f1, f2, in which the minima occur in the damping curve, are given by the capacitances C1 and C2 of the capacitors K1, K2, K3, K4.

FIG. 3 shows the outer structure of a multiple resonance filter, in which the external contacts 71, 72 are arranged on the end sides of the base body 1 in the form of a cap. The cap-shaped arrangement of the external contacts 71, 72 has the advantage that the component is suitable for surface mounting technology. In this case, the outer contact 71 is applied to the end face 81 of the main body 1 and the outer contact 72 is applied to the end face 82 of the main body 1.

The FIG. 31 shows a section along the line CC of FIG. 3 , The superimposed dielectric layers 4 can be seen, which are separated from one another by electrode layers 52, 62. As in the example of FIG. 31 the contacting of the electrode layers 52, 62 takes place via the end faces of the main body are in FIG. 31 the electrode layers 52, 62 are not pulled out to the outer lateral edge of the main body. The electrode layers 52 belong to a multilayer capacitor, wherein the electrodes 52 are all interconnected in parallel. The electrode layers 62, which in turn are stacked just like the electrode layers 52, also belong to the same multilayer capacitor as the electrode layers 52 and are arranged laterally offset to the electrode layers 52. Out FIG. 31 The comb-like intermeshing of the electrode layers 52 and 62 also emerges. In FIG. 31 For example, the electrode layers 52 are indicated by solid lines, while the electrode layers 62 are indicated by a dotted line. This applies analogously for the Figures 31D . 32 . 32D . 33 . 33D . 34 . 34D . 41 . 41D . 42 . 42D . 51 . 51D . 52 and 52D ,

The multilayer capacitors described here are in principle all constructed as in FIG. 31 shown. This applies in particular to the comb-like intermeshing of the electrode layers.

Figure 31A shows a section along the line AA FIG. 31 , It can be seen that three multilayer capacitors K1, K2, K3 are arranged in the interior of the multilayer component. The two outer capacitors K1, K3 in this case have electrode layers 51, 53 and 61, 63, which have the same areas. Therefore, the capacitors K1 and K3 have the same capacity. In contrast, the multilayer capacitor K2, which is arranged in the middle of the row of capacitors K1, K2, K3, has electrode layers 52, 62 which are larger than the electrode layers 51, 61, 53, 63. Accordingly, the capacitor K2 has a larger capacitance as the capacitors K1 and K3. In Figure 31A For example, the electrodes lying in the section plane are shown as hatched areas bounded by solid lines. In an overlying or underlying level arranged electrode layers, these are in particular the electrode layers 61, 62, 63 and the inner connecting element 92 are represented by areas bounded by dashed lines. In Figure 31A It is shown that the electrode layers 51, 52, 53 are interconnected by an inner connecting element 91. The inner connection member 91 may be formed in the same manner as the electrode layers 51, 52, 53. It can be used for example in multilayer technology be formed of a metal-containing paste. The connecting element 91 is contacted directly with the external contact 72. Accordingly, for the electrode layers 61, 62, 63 there is an inner connecting element 92, which electrically conductively connects these electrode layers 61, 62, 63 to one another. The inner connection element 92 is electrically conductively connected to the outer contact 71. As a result, an internal parallel connection of the capacitors K1, K2, K3 is realized.

FIG. 31D shows a section along the line DD Figure 31A , It is in an analog representation as in FIG. 31 4, 62, 63 (for the second contact of the respective capacitor, indicated by dashed lines) ) gives. The stacked electrode layers 51, 61 and 52, 62 and 53, 63 each form a multilayer capacitor K1, K2, K3. There are also the connecting elements 91, 92 in FIG. 31D shown. It should be noted that in the representation of FIG. 31D Also, the connecting elements 91, 92 are shown stacked in a plurality as a stack of connecting elements 91, 92.

FIG. 32 shows the internal structure of a multiple resonance filter accordingly FIG. 31 , but with the difference that only the inner connecting elements 91, 92 are shown. The inner connecting elements 91 are shown as dashed lines. The inner connecting elements 92 are shown as solid lines. Figure 32A shows a section along the line AA FIG. 32 , It is in an analogous way as in Figure 31A to recognize that the multiple resonance filter consists of four capacitors K1, K2, K3, K4, which in one to FIG. 31A, FIG. 31D and FIG. 31 analog fashion are constructed. The difference between the Figures 32, 32A and 32D to the Figures 31, 31A and 31D consists only in the number of capacitors. In Figure 32A is still a supply line 110 and a supply line 111 shown, from which it appears that with the aid of the leads 110, 111 inductances can be integrated into the device. The inductances over the length of the leads 110, 111 are determined. It is to be noted that the inductances of the device even from the shapes and surfaces of the electrode layers 51, 52, 53, 54 and 61, 62, 63 , 64, as in Figure 32A as a top view and in Figure 32D in cross-section, hang.

The Figure 32D shows a section along the line DD of Figure 32A , There are again four stacked electrode layers 51, 61 and 52, 62 and 53, 63 and 54, 64 shown. The construction is again according to the structure of FIG. 31D shown.

The Figures 33, 33A and 33D show a multiple resonance filter according to the FIGS. 31, 31A, 31D or according to the Figures 32, 32A, 32D with the difference that the electrode layers 51, 52, 53 and 61, 62, 63 in the embodiment according to the FIGS. 33, 33A, 33D not transverse to the longitudinal direction of the body, but extend in this longitudinal direction. Accordingly, the length of the inner connecting member 91, 92 is shortened, but the length of the electrode layers 51, 52, 53 and 61, 62, 63 is increased. The various embodiments regarding the orientation of the electrode layers 51, 52, 53, 54 and 61, 62, 63, 64 respectively show that there is a large margin in the design of the capacitances or inductances for the multiple-resonance filter. Otherwise the representation corresponds to the FIGS. 33, 33A, 33D the examples from the FIGS. 31, 31A, 31D ,

The Figures 34, 34A, 34D show an embodiment of the multiple resonance filter according to the FIGS. 33, 33A, 33D with the difference that four instead of three multilayer capacitors are formed in the device.

FIG. 4 shows an external structure for a group of multiple resonance filters, exemplified for this group in the Figures 41, 41A, 41D and 42, 42A, 42D are shown embodiments for the internal structure. FIG. 4 shows the multiple resonance filter with the base body 1, on whose side surfaces 101, 102 outer contacts 71, 72 are arranged.

FIG. 41 shows a section along the line CC of FIG. 4 , They are analogous to the representation in the Figures 31 . 32 . 33 . 34 Stack of superimposed dielectric layers 4 and electrode layers 52, 62 shown. The in the Figures 41, 41A and 41D The views of the multiple resonance filter shown differ from the representation in FIGS FIGS. 31, 31A, 31D only in that the contacting of the capacitors does not take place from the end faces of the base body, but from the side surfaces of the base body forth. Accordingly, the length of the leads 110, 111 z. B. in the Figures 41, 41A, 41D shortened, which is why in this embodiment, the inductance of the device is reduced. The FIGS. 41A, 41D each show sectional views, as they are analogous to the Figures 31A, 31D correspond.

The Figures 42, 42A, 42D show an embodiment for the multiple resonance filter according to the Figures 41, 41A, 41D with the difference that a plurality of four capacitors K1, K2, K3, K4 instead of three capacitors is formed inside the device. Otherwise correspond to the representations in the Figures 42, 42A, 42D the representations in the Figures 41, 41A, 41D ,

FIG. 5 shows an outer structure for a multi-resonance filter, wherein a base body 1 is provided. The main body 1 has end faces 81, 82. The base body 1 also has side surfaces 101, 102. On each side surface 101, 102 four external contacts 711, 712, 713, 714 and 721, 722, 723, 724 are respectively arranged. In this case, each opposing pair of external contacts 711, 721 or 712, 722 or 713, 723 or 714, 724 belongs to a capacitor in the interior of the main body 1.

FIG. 51 shows a section along the line CC of FIG. 5 , The representation in the FIGS. 51, 51A, 51D corresponds to the representation in the Figures 41, 41A, 41D , with the difference that here the connecting elements 91, 92 are missing, since each individual capacitor K1, K2, K3 individually with external contacts 711, 712, 713, 714 and 721, 722, 723, 724 (see Figure 51A ) connected is. Otherwise, the representation in the FIGS. 51, 51A, 51D the representation in the Figures 41, 41A, 41D ,

The Figures 52, 52A, 52D show the internal structure of a multiple resonance filter as it is with an outside structure FIG. 5 can be trained. The representation in the Figures 52, 52A, 52D corresponds to the representation in the FIGS. 51, 51A, 51D , with the difference that four multilayer capacitors K1, K2, K3, K4 are arranged instead of three capacitors K1, K2, K3 along the component. By the two middle capacitors K2, K3 with respect to their electrode layers 52, 53 and 62, 63 are formed so that they have the same capacitance C2, the damping behavior at the second resonant frequency f2 can be significantly improved again.

The invention is not limited to multi-resonance filters having two filter frequencies, but can be applied to multiple-resonance filters having a variety of different resonance frequencies.

LIST OF REFERENCE NUMBERS

• 1 main body
• 211, 212, 213, 214 first capacitor terminals
• 221, 222, 223, 223 second capacitor terminals
• 31, 32 contact
• 4 dielectric layer
• 51, 52, 53, 54 electrode layer
• 61, 62, 63, 64 electrode layer
• 711, 712, 713, 714 external contact
• 721, 722, 723, 724 external contact
• 71, 72 external contact
• 81, 82 front side
• 91, 92 inner connecting element
• 101, 102 side surface
• 110, 111 supply line
• C1, C2, C3 capacity
• K1, K2, K3, K4 condenser
• S insertion loss
• f frequency
• f1, f2 resonance frequency

Claims (16)

1. Multiple resonance filter as a multilayer component

   - comprising at least three multilayer capacitors (K1, K2, K3, K4) lying next to one another and having at least two different capacitances (C1, C2, C3),

   - the two outer multilayer capacitors (K1, K4) having the same capacitance (C1),

   - inductors of the multiple resonance filter being formed by electrode layers of the multilayer capacitors (K1, K4), and

   - the electrode layers engaging in one another in a comb-like manner.
2. Filter according to Claim 1,

   - in which the multilayer capacitors (K1, K2, K3, K4) are connected parallel to one another.
3. Filter according to either of Claims 1 and 2,

   - which has a main body (1) and has a stack of dielectric layers (4) lying one on top of the other with electrode layers (51, 52, 53, 54; 61, 62, 63, 64) lying in between.
4. Filter according to Claim 3,

   - in which external contacts (71, 72) of the electrode layers (51, 52, 53, 54; 61, 62, 63, 64) are arranged on the end faces (81, 82) of the main body (1).
5. Filter according to either of Claims 3 and 4,

   - in which electrode layers (51, 52, 53, 54; 61, 62, 63, 64) belonging to different capacitors (K1, K2, K3, K4) are connected to one another inside the main body (1).
6. Filter according to one of Claims 3 to 5,

   - in which electrode layers (51, 52, 53, 54; 61, 62, 63, 64) run in the longitudinal direction of the main body (1).
7. Filter according to one of Claims 3 to 5,

   - in which electrode layers (51, 52, 53, 54; 61, 62, 63, 64) run transversely to the longitudinal direction of the main body (1).
8. Filter according to one of Claims 3 to 6,

   - in which outer electrodes (711, 712, 713, 714; 721, 722, 723, 724, 71, 72) of the electrode layers (51, 52, 53, 54; 61, 62, 63, 64) are arranged on side faces (101, 102) of the main body (1).
9. Filter according to one of Claims 3 to 7,

   - in which the multilayer capacitors (K1, K2, K3, K4) are connected parallel to one another outside the main body (1).
10. Filter according to one of Claims 1 to 9,

    - in which three multilayer capacitors (K1, K2, K3) are provided.
11. Filter according to one of Claims 1 to 9,

    - in which four multilayer capacitors (K1, K2, K3, K4) are providepd, the two middle multilayer capacitors (K2, K3) having the same capacitance (C2).
12. Filter according to one of Claims 1 to 11,

    - in which the multilayer capacitors (K1, K2, K3, K4) together with inductors of the electrode layers (51, 52, 53, 54; 61, 62, 63, 64) and the supply leads (110, 111) form LC filters.
13. Filter according to one of Claims 3 to 12,

    - in which the dielectric layers (4) comprise a capacitor ceramic on the basis of barium titanate.
14. Filter according to one of Claims 3 to 13,

    - in which the electrode layers comprise a ceramic material with a varistor effect.
15. Filter according to one of Claims 3 to 14,

    - in which the main body (1) has a main area that is smaller than 6 mm².
16. Filter according to one of Claims 3 to 15,

    - in which electrode layers (51, 52, 53, 54; 61, 62, 63, 64) that belong to the two outer multilayer capacitors (K1, K4) have the same areas.

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